The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Suspension systems are employed to decouple a sprung element from impulse and vibration energy inputs that are experienced at an unsprung element by absorbing and dissipating vibration inputs. Suspension systems are employed on both stationary systems and mobile systems including passenger vehicles. Known suspension system elements include spring elements coupled in parallel and/or in series with damping elements, e.g., shock absorbers that include fluidic or pneumatic energy absorbing and dissipating features.
When employed on a vehicle system, suspension systems including springs and dampers are configured to coincidently provide performance characteristics related to passenger ride comfort, vehicle handling and road holding capability. Ride comfort is generally managed in relation to spring constant of the main springs of the vehicle, spring constant of passenger seating, tires and a damping coefficient of the damper. For optimum ride comfort, a relatively low damping force for a soft ride is preferred. Vehicle handling relates to variation in a vehicle's attitude, which is defined in terms of roll, pitch and yaw. For optimum vehicle handling, relatively large damping forces or a firm ride are required to avoid excessively rapid variations in vehicle attitude during cornering, acceleration and deceleration. Road holding ability generally relates to an amount of contact between the tires and the ground. To optimize road handling ability, large damping forces are required when driving on irregular surfaces to prevent loss of contact between individual wheels and the ground. Accordingly, in known passive suspension systems there is a fundamental tradeoff between ride and handling.
Known vehicle suspension dampers employ various methods to adjust damping characteristics to be responsive to changes in vehicle operational characteristics, including active damping systems. Active vehicle suspension systems employ actuators that control various suspension parameters to dynamically adjust one or more of passenger ride comfort, vehicle handling and road holding capability during vehicle operation in response to operating conditions. Such actuators are controlled by hydraulic, pneumatic, or other power sources that can consume on-vehicle power. A high amount of energy is required to change the spring and damper forces of the passive elements to achieve isolation and ride performance.